According to commonly accepted theories, the minimum hardware requirement for a gaze tracker is one camera and two light sources to enable gaze estimation with free head movements. However, in some scenarios, such as eye tracking on mobile devices, it is preferable to minimize components, particularly light sources. We propose a gaze estimation method using one camera and one light source.
A 'virtual light source' is introduced, geometrically positioned symmetrically to the real light source with respect to the camera, generating a 'virtual glint' in the captured image. We estimate the 'virtual glint' by exploiting the relationship between the distance of the two pupils and the two glints in the captured image, employing polynomial regression under the assumption of two available light sources. A new normalization factor for the regression method has been verified, proving practical for the one-glint system. Performance is shown to be acceptable, though degradation is noted compared to systems with two actual light sources.
Blogger's Review: This novel gaze estimation method using a single light source offers practical value, especially for mobile devices. Despite some performance degradation, the innovative introduction of a virtual light source showcases flexibility under hardware constraints, warranting further research and optimization.